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Fixing device and image forming apparatus

a technology of fixing device and fixing roller, which is applied in the direction of electrographic process apparatus, instruments, optics, etc., can solve the problems of large load on paper sheets, variable surface speed of heating fixing roller, and degradation of image quality

Inactive Publication Date: 2010-02-16
RICOH KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a fixing device and an image forming apparatus that can fix an unfixed toner image on a recording medium by heat and pressure. The fixing member has a deformable surface and a pressurizing member with an elastic layer that presses the endless member against the fixing member to bring them into pressure contact. The elastic layer has a larger apparent hardness than a point where its hardness changes rapidly with rubber thickness in a load application direction. This results in improved fixing performance and durability of the fixed image.

Problems solved by technology

Such local deformation at the nip exit, however, leads to variations in the surface speed of the heating-fixing roller (see FIG. 4 of Japanese Patent No. 3298354).
The variations in the surface speed of the heating-fixing roller leads to shifting of writing position of an image, which in turn leads to degradation in image quality.
This configuration, however, imposes a large load on the paper sheet, which disadvantageously leads to damage to the recoding medium and / or curling of the recoding medium.

Method used

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  • Fixing device and image forming apparatus
  • Fixing device and image forming apparatus
  • Fixing device and image forming apparatus

Examples

Experimental program
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first embodiment

[0020]FIG. 1 is a schematic diagram of a laser printer 100 that is an example of an image forming apparatus according to the present invention. The laser printer 100 includes a fixing device 20. The laser printer 100 includes a photoreceptor drum 1 as an image carrier. A charging unit 2, a developing unit 3, a transfer unit 4, a cleaning unit 5, a removing unit 6, and the like are arranged around the photoreceptor drum 1. A laser writing unit 7 is located above the exposure position on the photoreceptor drum 1 between the charging unit 2 and the developing unit 3, and the photoreceptor drum 1 is irradiated with a writing beam from the laser writing unit 7 at the exposure position.

[0021]A sheet feeding cassette 8 is provided at a lower portion of the laser printer 100. A sheet feeding roller 9, a conveying roller pair 10, a resist roller pair 11, and the like are arranged for feeding paper sheets in a nip portion between the photoreceptor drum 1 and the transfer unit 4. A fixing devi...

second embodiment

[0066]FIG. 7 is a schematic diagram of a fixing device 40 according to the present invention. The structural elements same as those of the fixing device 20 shown in FIG. 2 are given the same reference numerals, and explanation thereof is omitted below. The fixing device 40 can be used instead of the fixing device 20 in the laser printer 100 shown in FIG. 1.

[0067]The fixing device 40 includes an endless fixing member 41 as an endless member. The pressurizing unit 30 is brought into pressure contact with the endless fixing member 41. The fixing device 40 includes, inside the loop of the endless fixing member 41, a pressurizing member 42, a supporting member 43 that supports the pressurizing member 42, a pressing spring 44 as a biasing unit that presses the pressurizing member 42 and the supporting member 43 against the pressurizing unit 30, a friction-reducing member 45 that is positioned between the endless fixing member 41 and the pressurizing member 42 and reduces friction therebet...

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PUM

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Abstract

A fixing device includes a fixing member of which surface is deformable, a heating unit that heats the fixing member, a pressurizing unit having an endless member and a pressurizing member. The pressurizing member includes an elastic layer and presses the endless member against the fixing member to bring the endless member into pressure contact with the fixing member. The elastic layer has an apparent hardness (ASKER-C) which is larger than that at a point where an apparent hardness starts to change rapidly with respect to a rubber thickness in a load application direction.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present application claims priority to and incorporates by reference the entire contents of Japanese priority document, 2006-212374 filed in Japan on Aug. 3, 2006.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a fixing device of an image forming apparatus. More particularly, the present invention relates to a fixing device that includes an endless member that is brought into pressure contact with a fixing member.[0004]2. Description of the Related Art[0005]A heat fixing device is used in an image forming apparatus such as a copier, a printer, or a facsimile. A typical heat fixing device fixes an unfixed toner image onto a paper sheet by use of heat and pressure. For example, Japanese Patent No. 3298354 discloses a conventional heat fixing device that employs a belt-nip system. In such a belt-nip system, a fixing member, such as a fixing roller, is brought into pressure contact with an ...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): G03G15/20
CPCG03G15/2053
Inventor YAGI, MASAHIROFUKUHATA, YOSHIHIROOBATA, SHIGERU
Owner RICOH KK